Mucus is a complex, viscous, and adherent secretion that lines all body cavities exposed to the external environment. Mucus contains salts, surfactants (e.g., fatty acids, phospholipids, and cholesterol), and proteins, though 95% of it is water. The main component that is responsible for its viscoelastic gel-like properties are mucins, which are a class of high molecular weight (from 0.5 to 20 MDa) glycoproteins. Mucus provides a medium for localized drug delivery through mucoadhesive materials. Drug delivery vehicles that are localized in and retained by mucus can be used to efficiently target specific tissues to achieve systemic delivery over a long period of time to enhance the bioavailability of drugs.
Polymeric hydrogel materials with mucoadhesive properties are particularly interesting for controlled drug release to the surface of a specific mucosal tissue. Acrylic-based polymers have been extensively used for mucoadhesive applications because they exhibit very high adhesive bond strengths when in contact with mucosal tissues. In addition, these polymers exhibit pH responses. In acidic media, an acrylic-based copolymer is neutrally charged, and possesses intermolecular hydrogen bonding interaction, whereas in a basic environment, the PAA groups ionize to be negatively charged, which results in repulsion of the PAA chains from each other.
In parallel with the development of mucoadhesive polymers, progress has been made in hydrogels for sustained drug release. Of particular significance, sol-gel two-phase coexistence has been reported for the self-assembly of poly(ethylene glycol) (PEG) that is modified at both ends with fluoroalkyl groups (Rf-PEG-Rf). It has been shown that the gel and viscoelastic properties could be adjusted by varying the PEG midblock length, the Rf end group molecular weight, or both. By choosing the lengths of the hydrophilic PEG and hydrophobic Rf end groups, the type and rate of the erosion of the hydrogel can be controlled. An impressive feature of this system is that the gel phase maintains an equilibrium composition during the erosion process. Erosion occurs in a predictable manner through desorption of the micelles from the sol-gel interface. PEG-based hydrogels are widely used in biomedical applications. Thus, the Rf-PEG-Rf system is a promising template for drug delivery depot and controlled and sustained drug release.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.